Pump Element: Don't Touch That Dial!
 

I don't want to.

BUT, it looks like the p.o. used some hokey-pokey copper washers, which are now seized in the bores of the pump elements. And leaking.

I'm aware that the seals need to be fished out -- normally -- due to expansion from compression stresses. I typically carefully pry them out with a stainless dental pick.

These are much worse than that.

http://franklynb.home.mindspring.com...mp-element.jpg
For clarity, here's the style of element/delivery valve arrangement I have on this MW pump. Valves are #50, washers are #47. #53 is pump element. #62 is a shim.

The washers I'm considering R&R are swaged into the pump element counterbore so badly that I need to put them ON A MILL and machine them out for removal.

Obviously, this will require that I remove, and restore the pump elements.
As an aside, one also has a leaky o-ring. I'll replace them all "while I'm in there".

I know, I know. This also means that I should send the pump out for alignment. BUT, this is my "go ahead. make my day" rusty, trusty winter beater. Our four lane city streets are down to 2.5 lanes with ice encroachment. It doesn't pay to park/drive anything you aren't ready to lose to a snow plow.

A pump alignment will cost more than the car is worth, as my local bosch dealer can only tune <send to a stand> a repaired pump.

Call it $1200 +-$1K.

So. To the experts. There is no need to repeat the time-honored mantra "you could screw the pump, and the engine, beyond recognition!"

I get that. On to the question of the day:

Can I use the drip method, in sequence on each port, to tune the pump element positions?

In other words: drip test to spec; pull #2; fix it; restore it; crank to 24d + offset where required. set element position to the measured drip rate;
ibid #3, #4, and finally, #1. Repeat as required to get uniform readings.

I'm posting this in the "less travelled" Perf Tuning board in the hopes of having hard-heads weigh in. The thread on glow plug "tuning" got me to thinking. I'm not convinced that a glow plug is linear enough to compete with an EGT sensor, but thats another matter enitrely.

At a glance, the drip method would seem to be a technically sound predictor of "initial fuel rate" -- if carefully performed. I'm talking stopwatch, and perhaps a fuel pressure monitor. I'm not planning to change the shims, as I have no way to re-shim the pump elements correctly. <I suspect this is problematic, as the shim and pump element are a performance-matched tuned set, right?>

However, the leaks are progressive, and bad enough that I can't get a drip test to accurately predict fuel rate anymore -- so I'm forced to do something before spring.

Which ain't anywhere near Wisconsin.

Weigh in, please.

--frankb

I assume this is for an OM617? If so, I have a good injection pump that I can sell you. PM if you are interested.

If you don't go the used pump route, I would very carefully mark the position of each element before removal. If you put each element back where it came from, along with the corresponding shims etc, and line it up, you shouldn't need a calibration...

Find a used injection pump and replace your pump.

Don't even think for a second that anything you do can properly time it like a $100,000 bench machine. Its a RPITA to get them flowing evenly with a bench machine. Fractions of an inch make a significant difference.

I am so going to prove you wrong one day FI.

I'll be too elderly to prove you wrong by then. ;)

Ummm .... and how does one validate that the pump elements on a used pump haven't been disturbed since last setup, exactly?

And I get that a drip test will probably not out-perform four figures worth of service, by a professional on a six figure test stand.

However, that is not the question. I'll try to re-state it more clearly:

On my 616, can I expect to restore its present performance by carefully aligning the elements using the drip method?

Here's an observation: The Factory, in volume 1, suggests that one should check the drip on port #4, validating whether the pump needs service.

<Note: There are precious few objective measures of pump serviceability. Especially field bench tests. See first question above.>

So, if I check all four, and they are closely matched to an accurately projected set <pair, which simplifies matters greatly> of timing marks:
can I make the reverse inference --- plausibly infer that the pump can be restored to previous service levels?

Thats what the yellow paint on the nuts is for, tamper proofing. If they have been disturbed the paint will crack.


No. The drip tube is a coarse adjustment/testing method. You can get it close, but it won't be exactly timed with the other ports.

Your local Diesel injecton shop should be able to repair your pump. I was quoted "a couple hundred" for running mine across their BOSCH test bench.

the injection pump calibration i beleive measures the amount of fuel injected per cycle measured over many cycles and set to the spec.you could theoretically measure this on the car by collecting the fuel and comparing each element having run the engine for the same duration each time.the other spec would be the vertical position and travel of the individual plungers coming to engine tdc.probably best measured with a dial indicator.the adjustment process here would be shimming under each plunger.considering the precision requirements of these measurements and adjustments a fairly reasonable fee charged by a expert fuel injection for this service would seem to make sense:)

It would if there was any structure to that paragraph! :dizzy2:

:D sorry for the train of thoughts composition.

Personally I don't see why you shouldn't be able to do it this way....

All the same parts (except for washers and seals) so nothing needs to be 'compensated for' or altered because of a change of part.

Do each one in turn, setting the engine position for exactly 1 drip per second on the element to be worked on, and after re-fitting set again to exactly 1 drip per second...No Problem!-
-OK, It aint gonna be as accurate as a Bench Test set up in accordance with the ISO Test-Plan, but better than pissing out valuable expensive fuel everywhere, and Infinitely Cheaper than a S/H Pump!!:eek:

Naysayers are often brainwashed by gloom and doom stories/myths told by Fat-Cat Injection-Shops and 'idiot' mechanics....who have their own adjendas-
-Why do you think the owners of such places all drive round in Jags!! (Because its a Rip-Off Trade, Has been for years!)

Unless you Try, You'll Never know!!--If I was in the same position, I would do exactly as you plan. I have often repaired items including FI systems/pumps etc, that I have been told was impossible without 'special-tools/knowledge' but with a bit of planning and lateral thinking has all worked out.....

If you have the time, parts/seals etc,-Go for it!!:D

you can get it within spec by hand. i have done it multiple times yes its not going to be friggen perfect but what do you expect from something thats free?

I say you do it and succeed.

Just because you did it does not mean you should have done it in the first place.